Liquid Level Calculations for Trailer Tanks

[mminford]

We refurbish trailers and out source our liquid level calculations. Does anyone know how to calculate them for the different size trailers? They can range anywhere from 3000 Gal. to 6500 Gal. and possibly above. I know the slope of the trailer has to be considered. If you need any more information, I will be glad to give it.

 

[iainuts]

The way tank manufacturers come up with charts is to first determine the liquid volume as a function of height. You can do this by calculating the volume of a cylinder (laid on it's side for a trailer) and add to that the volume of the heads. Now you have the liquid volume and gas volume.

Next, you assume the fluid (liquid and gas) is saturated at some given pressure, so the charts are often given at various tank pressures. With the density of the saturated liquid and gas, you can calculate:
1) The total product in the tank.
2) The difference in pressure between the top and bottom of the tank.